Do Vertically-Migrating Animals Fertilize the Deep Chlorophyll Layer of Lake Superior?

Project Summary

Analogous to spreading manure on cropland, fish and invertebrates venturing en masse from Lake Superior’s deep waters to feed near the surface at night could spread essential nutrients to the algae layer that forms each growing season at about 30 meters deep. Researchers speculate that this unquantified internal cycle contributes to the outstanding discrepancy between measures of carbon input and carbon output in Lake Superior. This study is the first full top-to-bottom characterization of pelagic primary productivity. A combination of hydroacoustic data, measures of primary productivity, and examinations of nutrient use and exchange promise to yield results that will help Great Lakes fisheries make better-informed decisions about harvest rates and predictions associated with climate change. Results will add to ongoing contaminant studies and ecological research.